waste pipe run advice

[reeves1985]

Looking for a bit of guidence on how's best to run wastes for bath and basin
Due to a remodel I now have no other option but to tee the basin waste into the bath waste be for it goes outside to the soil stack

I have managed to find a route for the waste plumbing that will give sufficient fall and also as straight run as possible

As you can probably guess the basin has been moved to the other side of the room for practicality reasons as the room is such a small room

The existing bath waste is maybe about 500mm max before it reaches outside

I am going to have to tee into the within this 500mm area

What I need to know is the best way to eliminate any siphonage or smells etc and I don't want any backflow to enter the bath either as I have heard mentioned can happen if not done correctly

The basin waste itself will have a short cortical before starting it's horizontal length

Thanks

 

[plumben]

Anti vac traps

 

[Ch4 plumbing]

If you have plenty of fall and you have the tee round the right way the only reason you should get water coming up through the bath trap is if the waste is blocked just before the soil pipe.

 

[nysk2008]

1.5 inch bath and 11/4 basin waste will be fine reduce at the tee piece for the 11/4 waste

 

[kirkgas]

If the wash hand basin has a longish run, even inside max allowed I would run it in 38mm on it's horizontal run,

 

[Ermintrude]

Fit polypipe 32mm Aav

 

[Grumpy old Plum]

Fit polypipe 32mm Aav

HI
Make it a 50mm trunk waste system with 50 x 40 x 32 mm tee with anti vac traps and if possible air admittance valve above front rim height of basin.
regards
Grumpy old plumb

 

[Whyme]

As above 2" float to the stack.

 

[craigy]

Fit an anti air vac trap to bath and basin, increase basin waste to 40mm pipe as soon as practical. Increase bath waste to 50mm pipe as soon as practical and use a reducing insert for the tee, and make sure the tee is fitted the right way round.
You can then run with 10/100 mm fall with no worries of flow restrictions and hydraulic jumping.
That is playing it on the safe side.
hope that helps

 

[reeves1985]

Sorry for the late reply

I appreciate all the replies without wanting to go against the grain I already run part If the basin waste in 32mm which is the longest part on the horizontal will 32mm be ok or do I need to up it to 40

The only reason I ask is because of the placement of said pipe it had to go in first before other plumbing which is all rigid copper which will make it a pain to remove to replace

If needs must and all advice is to run 40mm basin then I am not against ripping it out to start fresh it would just mean a lot more work

Maybe a error on my part for not checking /asking first but hey we all do it at some point

 

[reeves1985]

HI
Make it a 50mm trunk waste system with 50 x 40 x 32 mm tee with anti vac traps and if possible air admittance valve above front rim height of basin.
regards
Grumpy old plumb

Thanks grumpy ;-)
Unfortunately it's not possible to get a air valve above basin height due to the location of basin and existing plumbing to soil stack (may make no difference but the stack itself is open vent at the top at roof level)

 

[newcastle phill]

How longs run from basin to tee point

 

[reeves1985]

How longs run from basin to tee point

The run is roughly 2.5m
The bathroom itself is only 2.8m x 1.5m

 

[newcastle phill]

I really think anti vac traps are overkill and an unnecessary expense.
Just size the pipe properly, have the basin and bath sufficiently trapped and falls not too severe.

 

[reeves1985]

I really think anti vac traps are overkill and an unnecessary expense.
Just size the pipe properly, have the basin and bath sufficiently trapped and falls not too severe.

Thanks Phil

The basin waste is in 32mm and as I say the run is a out 2.5m with a drop of about 50mm although this can be altered and the basin waste drops vertically about 400mm straight from waste

The bath waste basically will just go straight into the tee joining the two and out the wall to stack which is prob abily only 400mm max

 

[newcastle phill]

Cant see a prob.
Baths in 40mm ?
Just get a 32 into 40 tee.

Job done.
If its boxed in and no access.
Do it all in solvent weld and not push fit.

 

[reeves1985]

Cant see a prob.
Baths in 40mm ?
Just get a 32 into 40 tee.

Job done.
If its boxed in and no access.
Do it all in solvent weld and not push fit.

Yup bath is 40mm
All pipework is accessible at joins etc I just had to get creative to run it around a very small chimney breast which hugs the bath so I run the waste behind the plumbing to keep it neat so I am able to get fixings to hold the pipe and keep the fall

The tee will be directly after bath trap and straight out to soil pipe

It's amazing how you can make a tiny bathroom appear bigger by getting a bit creative and just moving a basin which up to now the only compromise is having to tee into the bath waste instead of separate runs